Additive & Subtractive Colour

Computer monitors, projectors, iPods, smart phones, television screens, etc. work much the way our eyes work. They emit red, green, and blue light and the combination of these three lights in various quantities and intensities produces the millions of colours we see on the screen.

When the three lights are beamed in the same proportion and intensity, the result on the screen is white. When no light is emitted, the result is black.

This system of producing colours is called additive because the three primary lights (red, green, blue), are added together to form the white light.



Producing colours by mixing pigments is called subtractive because pigments absorb (or subtract) light from the white light that hits the paper. Only the wavelengths that are reflected combine in our eyes to indicate the colour that we see.

In paint or pigment, the subtractive primary colours are red, yellow, and blue. Other colours result when primary or secondary colours are mixed.



In most colour printing, the primary ink colours use cyan, magenta, and yellow. Cyan is the complement of red, meaning that cyan acts as a filter that absorbs red. The amount of cyan applied to a paper controls how much red shows. Magenta is the complement of green, and yellow is the complement of blue. Black ink is added to the mix to obtain a real black and to give more depth to printed images. This mixture is called CMYK and is also known as four-colour process printing. Other colours are produced by dot patterns of cyan, magenta, yellow, and/or black.

video  The Graphic Designer's Printer